lttng.ust: Update lib load/unload events for LTTng 2.9

lttng.ust: Update lib load/unload events for LTTng 2.9

LTTng 2.9 adds new "lttng_ust_lib:{load|unload|build_id|debug_link}"
events, which should be used instead of the lttng_ust_dl:* events
to track library loading and unloading.

See https://bugs.lttng.org/issues/1035

Bug: 497351

Change-Id: I3a7631afd1ea6701e5bc7e2a5b24919a4ec7eee6
Signed-off-by: Alexandre Montplaisir <alexmonthy@efficios.com>
Reviewed-on: https://git.eclipse.org/r/77177
Reviewed-by: Hudson CI
Reviewed-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Tested-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>